This disclosure relates to a generator stator, and more particularly, the disclosure relates to a stator winding configuration.
Concentric windings are typically used in stator windings of high voltage DC generators. Such winding configurations are typically easy to wind and inexpensive in that the windings can readily be automated using existing equipment.
In conventional or typical concentric windings, the coils of the phase groups are nested and concentrically disposed about a common axis with the innermost coils spanning a smaller portion of the pole pitch and the outermost coils spanning a larger portion of the pole pitch. The conductors of the opposing sides of the coils of the phase groups are typically located in adjacent slots. The coils of the phase groups are progressively larger in span starting from the innermost coils that span a smallest portion of the pole pitch to the outermost coils that span the largest portion of the pole pitch. The outer most coils in the nests typically span a full pole pitch.
One drawback of a typical winding configuration is that the position of the conductors relative to other conductors within the winding produces undesirable harmonics in the magnetomotove force (MMF) waveform and stator winding terminal voltage waveforms. As a result, this type of winding is less favorable for use in constant speed, constant frequency and variable frequency generators that require terminal voltage waveforms that are more sinusoidal. These harmonics can lead to poor power quality, extraneous noises in communication equipment in close proximity, and parasitic losses and heating in the machine.
One type of single layer winding configuration uses concentric coils having opposing sides that are interspersed with the opposing sides of coils of the other phase. While this approach may reduce some harmonics in single layer winding configurations, undesirable harmonics remain.